Often during construction or fabrication of objects which utilize driven fasteners such as nails, a need arises to extract a previously driven or embedded nail and remove it from the object in which it is embedded. Most commonly, objects fabricated during construction of dwellings or similar buildings are structured using multiple sets of wooden boards having a plurality of nails driven into the boards at their various joints to secure the boards with respect to each other. The common nail utilized in such dwelling or building fabrication comprises a shank portion usually cylindrical having a sharp point at one end and an extending or expanded head at the other. In the typical nailing or driving operation the nail is driven into the board point first by multiple blows to the head with a hammer or similar driving object. At completion of the driving operation, the shank and point are buried in the wooden board and the head portion is at or slightly embedded in the outer surface of the board. The shank portion of the driven nail is securely gripped by the resilient forces of the wooden object. In many instances, various surface designs are used on the nail shank to improve the nail's "holding force" within the wood.
In the event it is desirable to remove an embedded nail, most fabricators resort to a device generally referred to as "puller" or "nail puller". While the particular designs and constructions of the nail pullers are subject to considerable variety, in their most basic form they comprise a pair of jaws adapted to grip the nail shank beneath the nail head, a handle portion and a lever portion. Generally, the lever portion is coupled to one of the jaws to provide a closing force during the pulling operation. In the typical nail puller operation the jaws are set beneath the nail head upon the shank and a lateral force is applied to the handle portion causing the puller to pivot about the lever member and withdraw the nail from the board.
One such puller is set forth in U.S. Pat. No. 728,668 for a TACK EXTRACTER issued to W. H. Brown in which an elongated handle supports a static jaw to which a movable jaw is pivotally secured. The movable jaw terminates at one end in an elongated lever portion and a spring member is supported upon the static jaw so as to urge the movable jaw toward the open position when not in use to facilitate easy engagement with a nail.
U S. Pat. No. 700,757 issued to F. C. Fowler for a NAIL PULLER sets forth a puller having a static jaw secured to an elongated handle. A multiple piece movable jaw is fabricated by a pair of outer portions positioned on either side of the static jaw in a pivotal attachment. An intermediate piece forming the jaw portion of the movable jaw is riveted between the outer members in alignment with the static jaw. A lever portion is riveted to the other end of the outer portions of the movable jaw to provide a curved lever surface for operation of the puller.
U.S. Pat. No. 1,156,870 issued to P. Aiazzi for a SPIKE EXTRACTOR sets forth a puller having an elongated handle and static jaw formed of a single metal member. A movable jaw is pivotally attached to the handle and defines a lever portion extending away from the jaw portion and the pivotal attachment. The lever portion further includes roller bearing which permits the movable jaw lever portion to move with respect to the board surface during the pulling operation to facilitate a more vertical extraction of the embedded nail.
U.S. Pat. No. 943,322 issued to O. Soles for a FLIGHT EXTRACTOR sets forth a tool adapted to remove flights from a conveyor system having an elongated handle terminating at one end in a pivotally attached gripping member and a movable jaw comprising an S-shaped member terminating at one end in a similar gripping member having a pivotal attachment in alignment with the first gripping member. The S-shaped member is pivotally attached to an intermediate portion of the handle and functions in much the same manner as the above-described nail pullers to extract flights from the conveyor system.
U.S. Pat. No. 753,386 issued to Gerlach and Moore for a SPIKE PULLER sets forth a combination extracting tool having an elongated handle portion terminating at one end in a generally curved claw having a serration therein and defining a flat pointed end similar to the claw portions of a conventional carpenter's hammer. The elongated member further defines a static jaw extending oppositely from the curved claw member and a movable jaw slideably attached to the elongated handle member and linked thereto by a pivotal arm to provide a pair of jaws operable to embrace a nail head and extract the nail. Thus, the puller in U.S. Pat. No. 753,386 is operative in either a conventional claw puller or a movable jaw puller at the user's preference.
U.S. Pat. No. 4,097,02I issued to Loboda for a TIRE STUD PULLER sets forth a tire stud puller which includes a static jaw element and a pivotal element supporting a second jaw. A detachable lever member is secured to the static jaw and provides a fulcrum about which the puller rotates during use. Gripping means having a lock portion are coupled between the handle member and the movable jaw to provide the gripping force between the static and movable jaws. The gripping means functions similar to a conventional pair of locking pliers and include a release lever mechanism.
While the foregoing described puller structures provide some effectiveness in extracting an embedded nail or similar object, they are typically subject to a problem due to the relationship between the gripping force applied to the nail and the lateral or pulling force applied to the handle. In accordance with an important design feature of the prior art nail pullers, the lever member about which the puller pivots during extraction is coupled to the movable jaw such that a direct relationship exists between the pulling force applied to the handle and the gripping force applied between the jaws to the nail. While in many instances this relationship is desirable, a problem arises in that an excess in pulling force required to pull a difficult nail may produce efficient force between the jaws to sever the nail head from the nail. Once the nail head has been severed the pulling operation is rendered extremely difficult.
There arises, therefore, a need in the art for a means of utilizing the advantageous aspects of a puller in which the gripping force is related to the pulling force while avoiding the undesired result of cutting the head from the nail shank.